Graphical operating system with a Scheme userspace.
XtOS/S is my first real operating system. The kernel is written in C and Assembly. The userspace is written in Scheme which is interpreted at runtime. All code is run in ring 0 and the operating system does not use paging or any other form of memory protection. It is graphical and uses a heavily modified version of the MeME window manager. It has keyboard and mouse support and runs on most IA-32 computers.
Example Userspace Application
(define dx 1) (while #t (begin (define x 1) (define y 1) (term-clear) (while (< y 10) (begin (while (< x 10) (begin (wm-put-pixel stdio-window (+ 100 (* x (sin (+ x dx)))) (+ 100 (* x (cos (+ x dx)))) 7) (set! x (+ x 1)) )) (set! x 1) (set! y (+ y 1)) )) (set! dx (+ dx 1)) ))